Can't help much, I'm afraid.
MGCT and MGIV are rated at the same speed and (I think) share the same base. MGWT is rated a tad over a stop slower and has a cream base. In terms of tonal shift, this is easier to achieve the warmer the paper i.e. with MGWT, then MGIV with MGCT bringing up the rear. Prior to the Cooltone soup being launched I've achieved cool tones via MGWT in Fotospeed AU20 gold toner, but then you end up with the cream highlights courtesy of the base.
Note - there was an article in B&WP UK a few months back which claimed that you couldn't achieve a tonal shift with MGWT in gold toner. Fortunately, that's absolute pants! Give it 15 minutes and it goes cold, 20 and it goes steely blue-black, 30 and it goes blue. Not bad archivally either. Unfortunately their review of the new Ilford soups was written by the same chap, so I'm uncertain how much trust I'm prepared to extend to its findings...
I've tested MGCT RC back-to-back with MGIV RC and it just didn't seem to have quite as much 'snap' to it as the neutral paper (though that might have been down to old stock or duff equipment in the college darkroom I was using). I've tried MGWT & MGIV in the new Warmtone soup and liked both effects. MGWT was (predictably) the warmer of the two, but MGIV's shadows were nicely warm while the whites stayed pure. If the Cooltone soup can cool the shadows then that might be a good option.
I haven't tried the new Cooltone soup at all yet, but I have some and will be getting round to it eventually. I'd be interested in your findings
Not what you asked, but the best I can do...!
